A study examined the relationship between students' linguistic insecurity (writing apprehension) and writing performance. College students in three remedial and two freshman composition classes were administered a test of linguistic insecurity that included pronunciation items and choices of hypercorrect, colloquial, and nonstandard versions of sentences. When the results of this test were compared to students' journal writings and their first graded compositions in the course, the analysis indicated a significant negative correlation between a student's linguistic insecurity and the number of clause types and number of words per t-unit. The insecure students often had strikingly less sophisticated writing in essays for the teacher than in their writing for personal, friendly, and uncritical audiences. The more secure students had less gap between the quality of the two modes of writing than the less secure students. The students' case studies also demonstrated that linguistic insecurity increased the difference between the modes of writing in terms of quality of syntactic structures ("well-formedness"), detail of examples, and general fluency. Linguistically secure students tended to do less editing during composing, saving the editing for a later stage of their writing processes, while linguistically insecure students often self-edited as they composed. (RL)